Infection following repair or replacement implantations, such as orthopedic implants, is a devastating complication associated with increased patient morbidity, longer hospital stays, and increased costs to the health care system. In the case of total hip arthroplasty (THA) and total knee arthroplasty (TKA), the projected situation is particularly concerning. It has been projected that the number of primary THA and TKA procedures are expected to increase. The current annual incidence of periprosthetic joint infections (PJI) following TKA and THA is also projected to increase. Revision procedures due to infections are more expensive than revisions due to aseptic reasons. As such, the total economic burden of PJI has been projected to increase.
Persistent or recurrent infections have been reported in some of those patients that require revision surgery due to primary infection. One of the primary mechanisms by which bacteria resist decontamination and persist on implants is through the formation of biofilms. Staphylococcus aureus (S. aureus) and Acinetobacter baumannii (A. baumannii) are microbes of major concern. S. aureus is a gram-positive bacterium and is considered the main pathogen in infections around metallic implants. There is also a growing concern about the increased prevalence of methicillin-resistant S. aureus (MRSA) being isolated from infected orthopedic implants. A. baumannii is a gram-negative bacterium that is associated with implant biofilms and is being increasingly implicated in incidences of multidrug-resistance.
The bacteria in biofilms are significantly more resistant to antimicrobials as compared to planktonic bacteria. In fact, some biofilm infections are virtually impossible to cure with an antimicrobial (AM) alone and it is these persistent infections that necessitate the removal of orthopedic implants and debridement of the bone. Treatment options are limited for biofilm-associated implant infections. Typically infections are treated with broad-spectrum systemic antibiotics and/or revision surgery for possible lavage, debridement, implant removal, placement of local antibiotics, and perhaps implantation of a new device. However, with the current standard treatments, recurrence of orthopedic infections is frequently reported. In light of this, new approaches are needed for the prevention and/or eradication of device-related biofilm infections.